PTFE as the main material. Has excellent chemical stability, corrosion resistance, sealing, lubrication is not high viscosity and good aging endurance. Long-term work at a temperature of -180 ℃ to +250 ℃, in addition to the molten metal and liquid sodium  fluoride,  the ability of all  other  chemicals, boiling water is not from the king of change. The following are not allowed pollution is mainly used for environmental sanitary conditions, corrosive and other demanding, high-speed lines, easy to wear and other conditions.